1. Field
The following description relates to an apparatus for manufacturing a semiconductor, which is used in the course of various semiconductor manufacturing procedures including forming a film on a wafer.
2. Description of the Related Art
Generally, a semiconductor manufacturing apparatus is used for various semiconductor manufacturing procedures including annealing, diffusion, oxidation, and chemical vapor deposition. Furnaces as semiconductor manufacturing apparatuses can be divided into two kinds in which vertical or horizontal furnaces are used.
As a low pressure chemical vapor deposition furnace, a vertical type furnace is more often employed than a horizontal type furnace because the vertical type furnace produces fewer fine impurities such as particles than the horizontal type furnace. In addition, the vertical type furnace has a process tube positioned vertically so that a bottom area occupied by a lower strut can be beneficially reduced.
A conventional vertical type furnace will be described with reference to FIG. 1.
Referring to FIG. 1, a vertical type furnace 10 includes a heating chamber 11 having a heater, an outer tube 12, an inner tube 13, a flange 14, a boat 15, and a nozzle 16. The outer tube 12 is installed inside the heating chamber 11, the inner tube 13 is installed inside the outer tube 12, and the outer tube 12 and the inner tube 13 are mounted on the flange 14. The boat 15 is mounted in the inner tube 13 and in the boat, wafers W are loaded. The nozzle 16 is installed on the flange 14 and a process gas is injected through the nozzle 16 from an external source. The process gas ejected from the nozzle 16 flows between the boat 15 and the inner tube 13 to form a film on each wafer.
In the example shown in FIG. 1, the wafers W are loaded vertically in the boat 15 one by one. Thus, to increase productivity by processing more wafers W at one time, a larger number of wafers W should be loaded. Then, a height of the loaded wafers W is increased and accordingly the time for the process gas to form a film on each wafer W can be increased. This may restrict the increase of the number of wafers W to be processed at one time.
Additionally, in the vertical type furnace 10 shown in FIG. 1, after the process gas is supplied from a lower portion forms a film on each wafer W while flowing between the boat 15 and the inner tube 13, residual gas passes over a top of the inner tube 13 and is discharged externally through a space between the inner tube 13 and the outer tube 12. In the above case, since the process gas is supplied to the wafers W while moving upwards, not all wafers have a uniform film formed thereon.